The 16S ribosomal RNA neighborhood of ribosomal protein S20 has been mapped, in both 30S subunits and 70S ribosomes, using directed hydroxyl radical probing. Cysteine residues were introduced at amino acid positions 14, 23, 49, and 57 of S20, and used for tethering 1-(p-bromoacetamidobenzyl)-Fe(II)-EDTA. In vitro reconstitution using Fe(II)-derivatized S20, together with the remaining small sub...

The human/sheep xenograft model has proven valuable in assessing the in vivo hematopoietic activity of stem cells from a variety of fetal and postnatal human sources. CD34+/lineage- or CD34+/CD38- cells isolated from human embryonic stem cells (hESCs) differentiated on S17 feeder layer were transplanted by intraperitoneal injections into fetal sheep. Chimerism in primary transplants was establi...

The origin and evolution of the ribosome is central to our understanding of the cellular world. Most hypotheses posit that the ribosome originated in the peptidyl transferase center of the large ribosomal subunit. However, these proposals do not link protein synthesis to RNA recognition and do not use a phylogenetic comparative framework to study ribosomal evolution. Here we infer evolution of ...

A gene-replacement mutagenesis method has been developed for the anaerobic, sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough and used to delete dcrA, encoding a potential oxygen or redox sensor with homology to the methyl-accepting chemotaxis proteins. A suicide plasmid, containing a cat-marked dcrA allele and a counter-selectable sacB marker was transferred from Escherichia coli...

To understand how chloroplast mRNAs are translated into functional proteins, a detailed understanding of all of the components of chloroplast translation is needed. To this end, we performed a proteomic analysis of the plastid ribosomal proteins in the small subunit of the chloroplast ribosome from the green alga Chlamydomonas reinhardtii. Twenty proteins were identified, including orthologs of...

The present status of the solar neutrino problem is reviewed. The strongest motivation for new neutrino physics comes from the complete phenomenological failure of astrophysical solutions: (1) The standard solar model is excluded by each of the solar neutrino experiments. (2) The combined results of Homestake and Kamiokande are incompatible with any astrophysical solution. (3) Even if the Homes...

Patients undergoing total knee arthroplasty (TKA) who have hypersensitivity to metals usually receive hypoallergenic TKA implants. Coating of a standard implant is a common solution. Although in vitro tests have demonstrated reduction in polyethylene wear for these coatings, it is unknown whether these costly implants have a clinical benefit for patients. One hundred twenty patients undergoing ...

We reevaluated Enterobacteriaceae disk diffusion breakpoints for the tetracyclines published in the Clinical and Laboratory Standards Institute (CLSI) document M100-S16, which were (susceptible/resistant) >or=19 mm/or=16 mm/or=19 mm/<or=14 mm for minocycline. A collection of 504 recent clinical isolates of Enterobacteriaceae were test...

A lack of individual plastid ribosomal proteins (PRPs) can have diverse phenotypic effects in Arabidopsis thaliana, ranging from embryo lethality to compromised vitality, with the latter being associated with photosynthetic lesions and decreases in the expression of plastid proteins. In this study, reverse genetics was employed to study the function of eight PRPs, five of which (PRPS1, -S20, -L...

Steep genetic clines resulting from recent secondary contact between previously isolated taxa can either gradually erode over time or be stabilized by factors such as ecological selection or selection against hybrids. We used patterns of variation in 30 nuclear and two mitochondrial SNPs to examine the factors that could be involved in stabilizing clines across a hybrid zone between two subspec...